Lifting-magnet.



G. H. POTH.

LIFTING MAGNET.

APPLICATION FILED JULY 25. I9l3.

1 ,1 99,92 1 Patented Oct. 3, 1916.

4 SHEETS-SHEET I.

"191114 was 5 W00 Wm Patented Oct. 3, 1916.

SHEET 3.

4 SHEETS- G. H. POTH.

LIFTING MAGNET.

APPLICATION FILED Jun 25.1813.

Patented Oct. 3, 1916.

4 SHEETSSHEET 4.

GEORGE HEN Y POTH, or CINCINNATI, OHIO.

I LIFTING-MAGNET.

Specification of Letters Patent.

' Patented Oct. 3, 1916.

Applcation filed July 25, 1918. Serial No. 781,181.

. To all whom it may concern Be it known that I, Gnonon HENRY Porn, a subject of the German Emperor, and a resident of Cincinnati, State of Ohio, have invented certain new. and useful Improvements in Liftin -Magnets, of which the following is a ful and clear specification, variousforms of reduction to, practice being illustrated in the accompanying drawings and the novel features of my invention being more fully pointed out in the annexed claims. 3

My invention relates to lifting or pull magnets, provided with an armature, the

.. is the same movement of which is utilized to perform work such as for instance, operating brakes, switches,'or as a hammer and the like. Especially this new type of lifting magnet has been designed for a long stroke, which makes it particularly suitable for the use of I power hammers and similar apparatus. Long strokes cannot well be obtained in an economical way with the ordinary solenoid pull magnet on account of the large energy which this latter type consumes for a very long stroke, because of the large air gap at the beginning of the stroke. In this new type of magnet the air gap between armature and the field housing is very small and can be as small as practically permissible. The energy consume producing the field is thus reduced to a minimum. Moreover, this new ty of magnet has the advantage that the direction of movement of the armature can be reversed by reversing the direction of the current in one of its windings as will be explained below. Intact, the stroke of the armature can be made any. desired length within reason-- able limits. II I I I I While the pullin the ordinary solenoid pull magnet consists mainly of a pull between a fixed pole surface and the movable plunger which is a pure magnetic pull, that is, the

all between two adjacent surfaces, the pull in the new type is of a different nature and a pure electromagnetic pull, set a between a ma eticfield and a current lea in conductoifi dcated directly in this field. T e princile according to which my magnet operates involved in the rotation of a direct current motorarmature. It is based on the fact that a current conductor extending transversely through a magnetic field tends I structure or the current in the magnet coil for j the other direction, ac,-

cordingto passesthrough the conductor. Therefore -a repulsion exists between the-conductor and the field poles, which can be reversed with the cur-rent in the conductor. According to which part is madestationary, (the field leading conductors) either the former or the latter will move when the system is energized. These current leading conductorsarereferred to in the descriptionof the drawings as the power windings.

For the purpose of setting forth clearly the nature of my invention I have illustrated in the accompanying drawings a few forms which may be preferred for practical application, but it is to be understood that I do not wish to limit my invention to the use of any particular formjof construction which the 'ower winding is disposed on the armature; ig. 1 is a full view of a small portion of the armature showing how the power windings may be arran d on it without grooves; Fig.2 is a. section similar to that of Fig. 1, showin the power winding arranged stationary; ig. 3 is a similar sectional view showing the arrangement of Fig.

2 in tandem; Fig. 4 is a longitudinal vertical section of a magnet with extremely long stroke; Fig. 4 is a sectional view of a portion of the armature 4 shown in Fig. 4 showing a .magnetic equivalent of the grooves shown in Fig. 4; Fig. 5 is a modification of the form shown in Fig. 2 havin ture guided on a central guide; igs. dead 6 show a modification in which the lines of force produced by the field traverse the armature transversely; Fig. 7 shows a modification in which the armature is coneshaped at its ends; Figs. 8 and 9 are wiring diagrams; Fi 10 is a modified form for arranging the old winding and the stationary power windings; Figs. 11 and 12 show how slots may be provided in the magnetic housing to counteract-the effect of eddy-currents. I

Referring now toFig. 1 which illustrates the principle of my Invention, 1 is the magpet housing or irame made oi magnetic mathe direction in which the current I the arma feet 7.

terial to form the outside path for the lines of force. It is preferably round as shown. The ends of the housing represent the poles 2+2. 3 is the field magnet coil suitably fastened in the housing. .4 is the movable armature which carries the power winding, 5. This winding is wound preferably in one or several annular or also spiral grooves 6. It also may be wound directly onto the periphery of armature 4 as shown in Fig. 1*. It is a continuous winding in whichall turns are wound in the same direction, the same way as the coil 3. The housing 1 1spreferably split. into two or more parts for practical purposes andsupported by suitable The armature 4 is continued at both ends 8 and 9 with a smaller diameter and these end portions may-be either of the same material as armature 4 and integral with it, or be of non-magnetic material and fastened to armature 4 Y in any suitable way. The armature should be properly guided at both ends by suitable bearings 10 and 11 fastenedto the housing, for instance as shown. The linesof force produced by field coil 3 pass through the housing and the armature as indicated in dotted lines, and the clearance between housing and armature should be as small as practically permissible, in order toreduce the reluctance of the path of the flux and thus the energy consumption of the magnet coil 3 to a minimum.

The operation of'this magnet is obvious.

The magnet coil 3 which is preferably energized by a constant voltage sets up the magnetic field as explained. If then the power winding 5 which is located directly in the field, is energized from the outside (not shown in Fig. 1),-there will be set up a reaction between the magnetic field and the power winding 5, the mechanical pull of which is at right angles to the direction'of the lines of force passing from the armature to the poles, and also at. right angles to the direction of the'current inthe conductors of power winding. 5, as explained before. Hence the direction of the pull is in parallel or very nearly so to the axis of armature 4. Thus according to the law of action and reaction the magnet housing 1 will move in axial direction if the armature 4 is held stationary, and if the housing 1 is held stationary, as is intended in Fig. 1, armature 4- will'move 1n axlal direction. The dlrectlon of the movement depends solely upon the direction of the flux and the direction of the way' and whichis shown in Fi current in the power winding 5. When the polarity of one of these two is changed then the direction of the movement is changed.

Should both ends of the armature 4, that is the parts under bothpoles 2-2, carry winding 5, which-would be the most economical 1, then the direction of the current in both alves should .be'opposite, because of the opposlte d l'efi' magnet and power winding, as is shown in Figs. 8 and 9. The stroke in this construction is limited since a pull can only take place while the power winding is still in the range of its magnetic field, and it is clear that the power winding on the lower half of the armature will after a certain stroke enter the field of the upper pole and thus cause a counteraction. The useful range of the stroke appears from Fig. 1. The upward movement of the armature 4 terminating approximately when the uppermost coil of the armature winding 5 on the lower half' of the armature, stands level" with the top of the field magnet similar to a direct current motor, the power winding 5 will produce a magnetic crossfluX cwhich tends to distort the main field reducing therebythe magnetic conductivity and thus decreasing the main field produced by coil 3. To counteract such detrimental flux a compensation winding 51 may be disposed in thefield poles as shown, which should be best placed in series with the power winding 5 as is customary in D. C. motors. The active compensating conductors of winding 51 are, as in D. C. motors, disposed parallel to the conductors of power winding 5 and must, of course, in order to neutralize the distorting effect of winding 5, conduct current of opposite direction. The axes of windingv 51 may thus, for instance, be coincident with the axis of winding 5, being the simplest and best arrangement.

It will be noticed that the windings o and w of the power winding neutralize each other when the armature is in a position shown in Fig. 1, but when the armature moves to one or the other side one winding will overpower the other as the case may be turns will include either the total flux or only a part of it. The simplest and best arrangement would thus be the same as for compensating winding 51, that is, to have its axis coincident with the axis of po er winding 3. Of course winding 5. This arrangement requires-the least amount of copper and gives the best result. In can be made up of individual short circuited turns or the winding can be short circuited as a whole. Such short circuit windings will oppose any variation of the main flux.

Fig. 2 shows a construction in which both windings the magnet winding 3 and the power winding 5 are fastened on the stationary housing 1, while the movablearmature 4 carries no power winding at all. In this construction magnet winding 3 and power winding'5 are for practical purposes wound on a separate cylinder 12, which after being wound, is inserted in housing 1. In order to minimize the magnetic leakage the inner wall of cylinder 12 which forms the bottom of grooves 6 and where coil 3 is located, is made as thin as it is practically permissible for mechanical reasons. The samereference numerals as used in Fig. 1 also apply to Fig. 2 and the other figures described later. In Fig. 2 the poles 2-2 of the field are now located on armature 4 and not on the hous ing as in Fig. 1. It is also shown how this construction can be applied to power hammers, whereby 13 indicates the ram weight and 14 the anvil. The claims hereto anneXed, while referring to a lifting magnet, obviously also cover the application of the claimed structure for power hammers such as shown in Figs l and 4, as examples.

Also in this case, as also in all modifications to be described hereinafter, compensating windings 51 and short circuit windings 50, 52 may be provided for the same purpose as explained with reference to Fig. 1, wherever it should be necessary. In this case, the field poles being located on the movable element 4, the above windings must be provided on the latter as indicated.

Fig. 3 showsa tandem arrangement of the single construction shown in Fig. 2 and it will be clearly seen that this arrangement can be multiplied to any degree.

Fig. 4 shows a type for. unlimited stroke. Here the armature or plunger 4 may have an unlimited number of poles 2, and it will be seen, that the armature will travel or move as long as the poles 2 will be in the range of the power winding 5.

Fig. 4 shows an armature which can be used with the housing shown in Fig. 4 but in which the pull is set up by the use of materials of different magnetic permeabilities. It may be composed for instance of steel disks 15 and cast iron disks 16 arranged alternating in succession and mounted on a guide rod 17 of material *of high permeability, for instance steel. This entire construction of disks and rod 15, 16, 17 would in that case replace the armature 4 and be attached to the ram-weight 13 in Fig. 4.

Fig. 5 shows a construction similar to Fig. 2 but in which only the poles of the armature are arranged to be movable. The poles 2-2 are then best connected by a thin sleeve 18, which slides over the stationary inner core 19,-which is properly fastened at both ends. Here the pull may be utilized to a better advantage, since the weight of the armature to be lifted is much smaller now than in the other arrangements.

Figs. 6 and 6'} show another arrangement in which the flux does not permeate the armature axially, but takes its way transversely from the housing through the small air gap into the poles of the plunger and across to the opposite as indicated. clearly indicated Fig. 6 there are 33, 33 the outline of whose coils is shown in dotted lines. The illustration of .the coil forms is supplemented by Fig. 6, which is an end view of Fig.6. The power winding consists of two sets of c ils 30 and 32, one on each side, correspondingly with the field coils, and their form is indicated by the dotted lines in the set 33 which connect slots a-m, b.-b hh. Each of the The manner of winding-is in the two figures.

coils a k is therefore wound through two slots.

With the arrangements shown there aremany other possible modifications within the scope of my invention. It may be mentioned here that the power winding 5 must be located in relation to the magnetic field. so that the conditions necessary for setting up an electromagnetic pull are fulfilled, which conditions are similar to those in D. C. motors.

This new pull magnet construction may also be combined with the ordinary solenoid type magnet as shown in Fig. 7, which represents the upper part of the magnet. The cap 20 consists here of magnetic material so that at the same time a magnetic p'ull between the inner surface 21 of the cap20 and the upper surface 22 of armature 4 willbe produced. Furthermore, these surfaces are preferably cone-shaped as indicated.

Both windings, the magnet winding 3 and the power winding 5, may be connected in parallel'or in series and suitable resistances or other means employed for controlling the current according to the requirements. Wiring diagrams are shown in Figs. 8 and 9 as examples, but other arrangements may be made of course to suit particular demands. 5 are indicated withcorresponding reference numerals. In Fig. 8 the diagram shows how the field winding 3 and the power 36 the current in the powerwindings can side of the housing In. field windings 31, 31, and

In these figures the windings 3 and;

be reversed for the purpose described hereinbefore. Fig. 9 shows how the field and power windings may be connected in multiple whereby eachis controlled by its own variable resistance 37 and 38 respectively. Also here a pole changer 36 serves for reversing the current in the power windings. Of course, as a full equivalent the current in the field winding instead of the power winding may be reversed, and the reversal of the power winding current has been merely shown and claimed as an example.

In order to prevent leakage of the'flux at the upper andlower end of the magnet from the armature to the frame outside of the range of the poles, the guides 10 and 11 are to be made of non-magnetic material and non-magnetic spacing pieces 23 may be fastened on the ram weight 13, which also serve as guide shoes for the weight, as indicated in Figs. 2 and 4.

The interior of the housing and the armature do not need to be round, though this is the best shape for practical purposes. The windings are preferably all disposed on the magnet housing as shown in Figs. 2, 3 and 4. The heat generated in these windings is readily conducted to the housing and easily dissipated by the latter to the surrounding air, In apparatus of larger sizes there may be water or air ducts 24 provided in the magnet housing to cool it, while the apparatus is in operation. Such ducts are shown for instance in Figs. 2, 3, i, 5, 7 and 10.

Fig. 10 shows another modification, where each half of the power winding 5 is wound on a separate cylinder, 25 and 26, with the field magnet coil 3 inserted between the two while the magnet housing is transversely divided into two halves.

The eddy-currents generated by the varying intensity of the main field caused by the unequal distribution of windings o and w due to the movement of armature 4 may .be counteracted by the short circuit windings and 52 previously referred to which also will,.to a certain extent, help preventing eddy currents in those parts of the housing and cylinder which are exposed to a varying flux density due to the displacement of the poles while the armature is moving. However, those eddy currents can be best avoided by laminating these parts in the well lrnown way,'or by slotting them. Such slots are shown in'Figs. Ill and 12 at 39 where it may be seen that they extend in suitable number in radial planes. Of course, in case the power winding is disposed on armature a as shown in Fig. 1 the armature should be laminated or slotted similarly.

In the arrangements described above the power winding 5 is thought to be wound in such away that the plane of its individual turns is at right angles or very nearly 1,19e,ea1

so to the axis of the armature, in other words, the turns are thought to be wound with a pitch which requires either annular grooves (pitch:0) or helical grooves with a small pitch. The pull exerted acts then in the direction of the axis of the armature, as above explained. If now the grooves in cylinder 12 are of a very large pitch the resultant pull of the conductors of power winding 5 will form a certain angle with the axis of the armature, so that at the same time at each stroke the armature will be turned a certain angle about its axis. The resultant movement of the armature will be a screwlike movement, which for certain purposes may be of advantage.

What I claim is:

1. A lifting magnet of the character described, comprising a frame, a field winding disposed therein, field poles adapted to be energized by said field winding, a power winding located in the field produced by said poles and electromagnetically conducting means for supporting said power winding, the axis of both the field and the power winding being parallel to each other and included by both of said windings, said power winding when energized causing relative movement between itself and said field poles in a direction at right angles to the lines of force of said poles which cross said power winding.

2. A lifting magnet of the character described, comprising a frame, a field winding disposed therein, field poles adapted to be energized by said field winding, a power winding located in the field produced by said poles and electromagnetically conducting means for supporting said power winding, the axis of both, the field and the power winding being parallel to each other and included by both of said windings, said power winding when energized causing relative movement between itself and said field poles in a direction at right angles to the lines of force of said poles which cross said power winding, and means forv reversing the current in said power winding to reverse the direction of relative movement.

3. A lifting magnet of the character described, comprising a housing with a cylindrical bore, a correspondingly shaped frame rigidly secured in said bore, said frame being provided with circumferential grooves. a field winding and a power winding, said power winding being carried in the grooves of said frame, an armature reciprocatingly disposed within said field and power windings and having field poles adapted to be energized by Stlhlfifld winding, said poles being suitably disposed to cause their lines of force to cross said power winding, said field poles tending to more axially and in a direction at right angles to the lines of force across said power winding.

4;. A lifting magnet of the character described, comprising a frame, of circular cross-section, a grooved sleeve fitting closely within said frame and rigidly secured therein, a field winding and a power winding both disposedin the grooves of said sleeve, an armature reciprocatingly disposed within said field and power windings and having field poles adapted to be energized by said field winding, said poles consisting of solid annular collars around the armature suitably disposed to cause their lines of force to cross said power winding, said field poles tending to move in a direction at right angles to the lines of force crossing said power winding, and means for reversing the current in said power winding to reverse the direction of movement of said field poles.

5. A lifting magnet of the character described, comprising a housing with a cylindrical bore, a frame with circumferen tial grooves, said frame fitting tightly and rigidly in said bore, a field winding and a power winding both disposed in the grooves of said frame, an armature movably disposed in axial direction within said two windings having field poles located adjacent to said power winding and adapted to be energized by said field winding, whereby the lines of force from said poles cross said power winding, said poles tending to move relatively to said power winding in a direction at right angles to the lines of force crossing said power winding.

6. A lifting magnet of the character described, comprising a frame of magnetizable material, a field winding disposed therein and energized "by constant voltage, field poles adapted to be energized by said field winding, a power winding located in the field produced by said poles and electromagnetically conducting means for supporting said power winding, said power winding when energized tending to move relatively to said field poles in a direction at right angles to the lines of 'force of said poles which cross said power winding, saidfield poles bearing a short-circuit winding.

7 A lifting magnet of the character described, comprising a frame, a field winding disposed therein, field poles adapted to be energized by said field winding, a power winding located in the field produced by said poles and electromagnetically conducting means for supporting said power winding, said power winding when energized tending to move relatively to said field poles in a direction at right angles to the lines of force of said poles which cross said power winding, and a short circuit winding disposed on said field poles, and a like winding disposed between said power windings.

8. A lifting magnet of the character de. scribed comprising a frame, a field Winding disposed therein, field poles adapted to be energized by] said field winding, a power winding located in the field produced by said poles and electromagnetically conducting means for supporting said power'winding, the aXis of both, the field and the power winding, coinciding with each other, said power winding when energized causing relative movement between itself and said field poles in a direction at right angles to the lines of force of said poles which cross said power winding.

c. HENRY POTH.

Witnesses:

JNo. G. Rmsmo, LOUIS A. HAUGK. 

